import scala.annotation.*

trait C[@specialized U] {
  @unspecialized
  def foo(u: U): U
  @unspecialized
  def bar[A](u: U) = u
}

object Test extends App {
  val declared = classOf[C[_]].getDeclaredMethods.sortBy(_.getName)
  println(declared.mkString("\n"))
  object CInt extends C[Int] { def foo(i: Int) = i }
  object CAny extends C[Any] { def foo(a: Any) = a }
  assert(CInt.foo(1) == 1)
  assert(CAny.foo("") == "")
}
